The present invention relates generally to newly identified rdgB proteins and related products and methods.
The following discussion of the background of the invention and references cited therein are not admitted to be prior art to the invention.
Cellular signal transduction is a fundamental mechanism whereby external stimuli that regulate diverse cellular processes are relayed to the interior of cells. One of the key biochemical mechanisms of signal transduction involves the reversible phosphorylation of tyrosine residues on proteins. The phosphorylation state of a protein is modified through the reciprocal actions of tyrosine phosphatases (TPs) and tyrosine kinases (TKs), including receptor tyrosine kinases and non-receptor tyrosine kinases.
A tyrosine protein kinase named PYK2, is described in U.S. patent application Ser. No. 08/460,626, filed Jun. 2, 1995, which is a continuation-in-part application of U.S. patent application Ser. No. 08/357,642, filed Dec. 15, 1994, both of which are hereby incorporated herein by reference in their entirety including any drawings. PYK2 contains an N-terminal domain, a catalytic domain, two proline-rich regions, potential Src homology 2 (SH2) binding regions, and a region homologous to the focal adhesion targeting domain.
A type of protein found in Drosophila, called Drosophila retinal degeneration B protein(rdgB)is described in Vihtelic et al., J. of Cell Biology 122, :1013-1022, 1993. The sequence described in this reference, however, contained a false stop codon sequencing error and thus the authors were not aware that the Drosophila rdgB contains a PYK-2 binding domain. In addition, this sequence was incorrectly identified as a member of the 6-transmembrane domain family of proteins. These rdgB proteins function in many sensory and neuronal cells of the fly and are directly associated with sight in the fly.
The sequence of a genomic clone of a portion of C. elegans has been placed on a computer database, and (although unappreciated), this sequence contains an rdgB sequence with introns. Thus, the GENEBANK database contains raw data of the nucleotide sequence of a series of genomic clones of c. Elegans. Using portions of the human rdgb sequence, the present invention identifies an open reading frame that has been to this point unrecognized. An rdgB was thus found segregated into 14 exons in two separate cosmids C54C6 (assc. #Z77131) and MO1F1 (assc. #Z46381).
The present invention relates to rdgB polypeptides, nucleic acids encoding such polypeptides, cells, tissues and animals containing such polypeptides, antibodies to such polypeptides, assays utilizing such polypeptides, and methods relating to all of the foregoing. Such rdgB polypeptides are involved in various signal transduction pathways and thus the present invention provides several agents and methods useful for diagnosing, treating, and preventing various diseases or conditions associated with abnormalities in these pathways.
The present invention is based in part upon the identification and isolation of a series of novel non-receptor tyrosine kinase binding molecules, termed hrdgB1, hrdgB2, and hrdgB3. The full length nucleic acid sequences encoding these proteins are set forth respectively in SEQ ID NO:1, SEQ ID NO:2, and SEQ ID NO:3. The full length amino acid sequences are set forth respectively in SEQ ID NO:4, SEQ ID NO:5, and SEQ ID NO:6. RDGBs are generally comprised of 3 structural domains. The N-terminal PIT domains described herein have approximately 45% amino acid identity to human PPI1 and PPI2. The PIT domains of RDGB2 and RDGB3 (RDGB1 lacks a PIT domain) have approximately 72% identity with each other and approximately 62-65% identity with the drosophila and C elegans rdgB""s. The full length amino acid sequence for c. Elagans is set forth in SEQ ID NO:7 and the full length Drosophila nucleic acid sequence set forth in SEQ ID NO:8, and the full length Drosophila amino acid sequence is set forth in SEQ ID NO:9. The PIT domains of the rdgBs have a conserved putative ATP binding motif similar to that seen in protein kinases.
The second central domain is present in all human rdgbs described herein and has no sequence homology to any other known domain. The three human rgdbs share 43-47% identity over the 600 to 675 amino acid stretch and show 25-35% identity to the invertebrate rdgB""s. This large domain contains three subdomains with much higher identity (66-88% in the human rdgbs and 35-75% with the invertebrate rdbgs.) This high level of conservation, especially across such a diverse set of species, suggests an important functional role for these stretches. The N-terminal portion of the central domain is a conserved acidic region of 10 to 15 amino acids comprised almost exclusively of glutamatic and aspartate residues that may function as a calcium binding motif.
The third rdgB domain is particularly unique to these proteins and consists of the C-terminal 343 to 384 residues of the proteins. There is 60-63% identity amongst the human rdgbs and 40-60% with the invertebrate rdgB""s. The comparison with the drosophila rdgb is based on the unique knowledge of this domain and its functional significance as described herein. The published sequence contained a framseshift mutation such that the protein was previously thought to terminate less than halfway through this domain. By comparison with the human sequences, the present invention provides a sequence that extends beyond the end of the drosophila sequence to include amino acids 1054-1249.
Within the PYK2 binding domain is a distinct motif with primary sequence homology to the nucleotide binding region of the ras-related GTP-binding proteins. All members of this family (ras, rho, rac, rab, ran) contain a sequence characterized by the conserved hydrophobic-hydrophobic-G-X-K-X-D-hydrophobic amino acid sequence. The G-X-K motif in the rdgBs is at aa 614 (rdgb1), aa898 (rdgb2), aa 983 (rdgb3) and aa 987 (dm). Based on analysis of the three dimensional structure (by X-ray crystalography) of this region from ras and ran, this motif grasps the nucleotide ring of GDP/GTP as part of the molecular xe2x80x9con-offxe2x80x9d switch in these proteins. The rdgbs however lack the upstream p-llop or A-box present in these small G-proteins.
RdgB proteins are involved in key signal transduction pathways related to neurotransmitter signaling. This is based in part on the recognition of existence and significance of domains found in rdgB proteins (see FIG. 1). For example, the experiments described herein demonstrate that rdgB proteins contain a PYK2 binding domain. PYK2 is believed to be responsible for regulating neurotransmitter signaling. The rdgB proteins also contain a PIT domain, which in Drosophila is involved in PI transfer. PI transfer in humans is involved in the recycling of synaptic vesicles. Thus, in view of the roles of the PYK2 binding domain and the PIT domain, rdgB proteins may be useful in the treatment of conditions of nervous system by enhancing or inhibiting such signaling.
Thus, in a first aspect the invention features an isolated, purified, enriched or recombinant nucleic acid encoding a rdgB polypeptide. Preferably such nucleic acid encodes a mammalian rdgB polypeptide, more preferably it encodes a human rdgB polypeptide.
By xe2x80x9cisolatedxe2x80x9d in reference to nucleic acid is meant a polymer of 2 (preferably 21, more preferably 39, most preferably 75) or more nucleotides conjugated to each other, including DNA or RNA that is isolated from a natural source or that is synthesized. The isolated nucleic acid of the present invention is unique in the sense that it is not found in a pure or separated state in nature. Use of the term xe2x80x9cisolatedxe2x80x9d indicates that a naturally occurring sequence has been removed from its normal cellular environment. Thus, the sequence may be in a cell-free solution or placed in a different cellular environment. The term does not imply that the sequence is the only nucleotide chain present, but does indicate that it is the predominate sequence present (at least 10-20% more than any other nucleotide sequence) and is essentially free (about 90-950 pure at least) of non-nucleotide material naturally associated with it. Therefore, the term does not encompass an isolated chromosome encoding one or more rdgB polypeptides.
By the use of the term xe2x80x9cenrichedxe2x80x9d in reference to nucleic acid is meant that the specific DNA or RNA sequence constitutes a significantly higher fraction (2-5 fold) of the total DNA or RNA present in the cells or solution of interest than in normal or diseased cells or in the cells from which the sequence was taken. This could be caused by a person by preferential reduction in the amount of other DNA or RNA present, or by a preferential increase in the amount of the specific DNA or RNA sequence, or by a combination of the two. However, it should be noted that enriched does not imply that there are no other DNA or RNA sequences present, just that the relative amount of the sequence of interest has been significantly increased in a useful manner and preferably separate from a sequence library. The term significant here is used to indicate that the level of increase is useful to the person making such an increase, and generally means an increase relative to other nucleic acids of about at least 2 fold, more preferably at least 5 to 10 fold or even more. The term also does not imply that there is no DNA or RNA from other sources. The other source DNA may, for example, comprise DNA from a yeast or bacterial genome, or a cloning vector such as pUC19. This term distinguishes from naturally occurring events, such as viral infection, or tumor type growths, in which the level of one mRNA may be naturally increased relative to other species of mRNA. That is, the term is meant to cover only those situations in which a person has intervened to elevate the proportion of the desired nucleic acid.
It is also advantageous for some purposes that a nucleotide sequence be in purified form. The term xe2x80x9cpurifiedxe2x80x9d in reference to nucleic acid does not require absolute purity (such as a homogeneous preparation); instead, it represents an indication that the sequence is relatively purer than in the natural environment (compared to the natural level this level should be at least 2-5 fold greater, e.g., in terms of mg/ml). Individual clones isolated from a cDNA library may be purified to electrophoretic homogeneity. The claimed DNA molecules obtained from these clones could be obtained directly from total DNA or from total RNA. The cDNA clones are not naturally occurring, but rather are preferably obtained via manipulation of a partially purified naturally occurring substance (messenger RNA). The construction of a cDNA library from mRNA involves the creation of a synthetic substance (cDNA) and pure individual cDNA clones can be isolated from the synthetic library by clonal selection of the cells carrying the cDNA library. Thus, the process which includes the construction of a cDNA library from mRNA and isolation of distinct cDNA clones yields an approximately 106-fold purification of the native message. Thus, purification of at least one order of magnitude, preferably two or three orders, and more preferably four or five orders of magnitude is expressly contemplated.
By xe2x80x9crdgB polypeptidexe2x80x9d is meant 9 or more contiguous amino acids set forth in the full length amino acid sequence of SEQ ID NO:4, SEQ ID NO:5, or SEQ ID NO:6. The rdgB polypeptides can be encoded by full-length nucleic acid sequences or any portion of a full-length nucleic acid sequence, so long as a functional activity of the polypeptide is retained. Preferred functional activities include the ability to bind to the N-terminal portion of PYK2. For example, the present invention encompasses deletion mutants isolated domains, and complementary sequences capable of hybridizing to full length rdgB protein under stringent hybridization conditions.
In preferred embodiments, isolated nucleic acid comprises, consists essentially of, or consists of a nucleic acid sequence set forth in the full length nucleic acid sequence SEQ ID NO:1, SEQ ID NO:2, or SEQ ID NO:3 or at least 27, 30, 45, 60 or 90 contiguous nucleotides thereof and the rdgB polypeptide comprises, consists essentially of, or consists of at least 9, 10, 15, 20, 30, 50, 100, 200, or 300 contiguous amino acids of a rdgB polypeptide.
By xe2x80x9ccomprisingxe2x80x9d it is meant including, but not limited to, whatever follows the word xe2x80x9ccomprisingxe2x80x9d. Thus, use of the term xe2x80x9ccomprisingxe2x80x9d indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present. By xe2x80x9cconsisting ofxe2x80x9d is meant including, and limited to, whatever follows the phrase xe2x80x9cconsisting ofxe2x80x9d. Thus, the phrase xe2x80x9cconsisting ofxe2x80x9d indicates that the listed elements are required or mandatory, and that no other elements may be present. By xe2x80x9cconsisting essentially ofxe2x80x9d is meant including any elements listed after the phrase, and limited to other elements that do not interfere with or contribute to the activity or action specified in the disclosure for the listed elements. Thus, the phrase xe2x80x9cconsisting essentially ofxe2x80x9d indicates that the listed elements are required or mandatory, but that other elements are optional and may or may not be present depending upon whether or not they affect the activity or action of the listed elements.
Compositions and probes of the present invention may contain human nucleic acids encoding a rdgB polypeptide but are substantially free of nucleic acid not encoding rdgB polypeptide. The human nucleic acid encoding a rdgB polypeptide is at least 18 contiguous bases of the nucleotide sequence set forth in SEQ. ID NO. 1, SEQ. ID NO. 2, or SEQ. ID NO. 3 and will selectively hybridize to human genomic DNA encoding a rdgB polypeptide, or is complementary to such a sequence. The nucleic acid may be isolated from a natural source by cDNA cloning or subtractive hybridization; the natural source may be blood, semen, and tissue of various organisms including eukaryotes, mammals, birds, fish, plants, gorillas, rhesus monkeys, chimpanzees and humans; and the nucleic acid may be synthesized by the triester method or by using an automated DNA synthesizer. In yet other preferred embodiments the nucleic acid is a conserved or unique region, for example those useful for the design of hybridization probes to facilitate identification and cloning of additional polypeptides, the design of PCR probes to facilitate cloning of additional polypeptides, and obtaining antibodies to polypeptide regions.
By xe2x80x9cconserved nucleic acid regionsxe2x80x9d, are meant regions present on two or more nucleic acids encoding a rdgB polypeptide, to which a particular nucleic acid sequence can hybridize to under lower stringency conditions. Examples of lower stringency conditions suitable for screening for nucleic acid encoding rdgB polypeptides are provided in Abe, et al. J. Biol. Chem., 19:13361 (1992) (hereby incorporated by reference herein in its entirety, including any drawings). Preferably, conserved regions differ by no more than 7 out of 20 nucleotides.
By xe2x80x9cunique nucleic acid regionxe2x80x9d is meant a sequence present in a full length nucleic acid coding for a rdgB polypeptide that is not present in a sequence coding for any other naturally occurring polypeptide. Such regions preferably comprise 12 or 20 contiguous nucleotides present in the full length nucleic acid encoding a rdgB polypeptide.
The invention also features a nucleic acid probe for the detection of a rdgB polypeptide or nucleic acid encoding a rdgB polypeptide in a sample. The nucleic acid probe contains nucleic acid that will hybridize to at least one sequence set forth in SEQ ID NO:1, SEQ ID NO:2, or SEQ ID NO:3.
In preferred embodiments the nucleic acid probe hybridizes to nucleic acid encoding at least 12, 27, 30, 35, 40, 50, 100, 200, or 300 contiguous amino acids of the full-length sequence set forth in SEQ ID NO:4, SEQ ID NO:5, or SEQ ID NO:6. Various low or high stringency hybridization conditions may be used depending upon the specificity and selectivity desired.
By xe2x80x9chigh stringency hybridization conditionsxe2x80x9d is meant those hybridizing conditions that (1) employ low ionic strength and high temperature for washing, for example, 0.015 M NaCl/0.0015 M sodium citrate/0.1% SDS at 50xc2x0 C.; (2) employ during hybridization a denaturing agent such as formamide, for example, 50% (vol/vol) formamide with 0.1% bovine serum albumin/0.1% Ficoll/0.1% polyvinylpyrrolidone/50 mM sodium phosphate buffer at pH 6.5 with 750 mM NaCl, 75 mM sodium citrate at 42xc2x0 C.; or (3) employ 50% formamide, 5xc3x97SSC (0.75 M NaCl, 0.075 M Sodium pyrophosphate, 5xc3x97 Denhardt""s solution, sonicated salmon sperm DNA (50 g/ml), 0.1% SDS, and 10% dextran sulfate at 42xc2x0 C., with washes at 42xc2x0 C. in 0.2xc3x97SSC and 0.1% SDS. Under stringent hybridization conditions only highly complementary nucleic acid sequences hybridize. Preferably, such conditions prevent hybridization of nucleic acids having 1 or 2 mismatches out of 20 contiguous nucleotides.
Methods for using the probes include detecting the presence or amount of rdgB RNA in a sample by contacting the sample with a nucleic acid probe under conditions such that hybridization occurs and detecting the presence or amount of the probe bound to rdgB RNA. The nucleic acid duplex formed between the probe and a nucleic acid sequence coding for a rdgB polypeptide may be used in the identification of the sequence of the nucleic acid detected (for example see, Nelson et al., in Nonisotopic DNA Probe Techniques, p. 275 Academic Press, San Diego (Kricka, ed., 1992) hereby incorporated by reference herein in its entirety, including any drawings). Kits for performing such methods may be constructed to include a container means having disposed therein a nucleic acid probe.
The invention also features recombinant nucleic acid, preferably in a cell or an organism. The recombinant nucleic acid may contain a sequence set forth in SEQ ID NO:1 and a vector or a promoter effective to initiate transcription in a host cell. The recombinant nucleic acid can alternatively contain a transcriptional initiation region functional in a cell, a sequence complimentary to an RNA sequence encoding a rdgB polypeptide and a transcriptional termination region functional in a cell.
In another aspect the invention features an isolated, enriched or purified rdgB polypeptide.
By xe2x80x9cisolatedxe2x80x9d in reference to a polypeptide is meant a polymer of 2 (preferably 7, more preferably 13, most preferably 25) or more amino acids conjugated to each other, including polypeptides that are isolated from a natural source or that are synthesized. The isolated polypeptides of the present invention are unique in the sense that they are not found in a pure or separated state in nature. Use of the term xe2x80x9cisolatedxe2x80x9d indicates that a naturally occurring sequence has been removed from its normal cellular environment. Thus, the sequence may be in a cell-free solution or placed in a different cellular environment. The term does not imply that the sequence is the only amino acid chain present, but that it is the predominate sequence present (at least 10-20% more than any other sequence) and is essentially free (about 90-95% pure at least) of non-amino acid material naturally associated with it.
By the use of the term xe2x80x9cenrichedxe2x80x9d in reference to a polypeptide is meant that the specific amino acid sequence constitutes a significantly higher fraction (2-5 fold) of the total of amino acids present in the cells or solution of interest than in normal or diseased cells or in the cells from which the sequence was taken. This could be caused by a person by preferential reduction in the amount of other amino acids present, or by a preferential increase in the amount of the specific amino acid sequence of interest, or by a combination of the two. However, it should be noted that enriched does not imply that there are no other amino acid sequences present, just that the relative amount of the sequence of interest has been significantly increased. The term significant here is used to indicate that the level of increase is useful to the person making such an increase, and generally means an increase relative to other amino acids of about at least 2 fold, more preferably at least 5 to 10 fold or even more. The term also does not imply that there is no amino acid from other sources. The other source amino acid may, for example, comprise amino acid encoded by a yeast or bacterial genome, or a cloning vector such as pUC19. The term is meant to cover only those situations in which man has intervened to elevate the proportion of the desired amino acid.
It is also advantageous for some purposes that an amino acid sequence be in purified form. The term xe2x80x9cpurifiedxe2x80x9d in reference to a polypeptide does not require absolute purity (such as a homogeneous preparation); instead, it represents an indication that the sequence is relatively purer than in the natural environment (compared to the natural level this level should be at least 2-5 fold greater, e.g., in terms of mg/ml). Purification of at least one order of magnitude, preferably two or three orders, and more preferably four or five orders of magnitude is expressly contemplated. The substance is preferably free of contamination at a functionally significant level, for example 90%, 95%, or 99% pure.
In preferred embodiments rdgB polypeptides contain at least 9, 10, 15, 20, or 30 contiguous amino acids of the full-length sequence set forth in SEQ ID NO:4, SEQ ID NO:5, or SEQ ID NO:6.
In yet another aspect the invention features a purified antibody (e.g., a monoclonal or polyclonal antibody) having specific binding affinity to a rdgB polypeptide. The antibody contains a sequence of amino acids that is able to specifically bind to a rdgB polypeptide.
By xe2x80x9cspecific binding affinityxe2x80x9d is meant that the antibody will bind to a hrgdB polypeptide at a certain detectable amount but will not bind other polypeptides to the same extent, under identical conditions. The present invention also encompasses antibodies that can distinguish hrgdB1 from hrdgB2 or hrdgB3 or can otherwise distinguish between the various rdgBs.
Antibodies having specific binding affinity to a rdgB polypeptide may be used in methods for detecting the presence and/or amount of a rdgB polypeptide is a sample by contacting, the sample with the antibody under conditions such that an immunocomplex forms and detecting the presence and/or amount of the antibody conjugated to the rdgB polypeptide. Diagnostic kits for performing such methods may be constructed to include a first container means containing the antibody and a second container means having a conjugate of a binding partner of the antibody and a label.
In another aspect the invention features a hybridoma which produces an antibody having specific binding affinity to a rdgB polypeptide.
By xe2x80x9chybridomaxe2x80x9d is meant an immortalized cell line which is capable of secreting an antibody, for example a rdgB antibody.
In preferred embodiments the rdgB antibody comprises a sequence of amino acids that is able to specifically bind a rdgB polypeptide.
Another aspect of the invention features a method of detecting the presence or amount of a compound capable of binding to a rdgB polypeptide. The method involves incubating the compound with a rdgB polypeptide and detecting the presence or amount of the compound bound to the rdgB polypeptide.
In preferred embodiments, the compound inhibits an activity of rdgB. The present invention also features compounds capable of binding and inhibiting rdgB polypeptide that are identified by methods described above.
In another aspect the invention features a method of screening potential agents useful for treatment of a disease or condition characterized by an abnormality in a signal transduction pathway that contains an interaction between a rdgB polypeptide and a natural binding partner (NBP). The method involves assaying potential agents for those able to promote or disrupt the interaction as an indication of a useful agent.
By xe2x80x9cscreeningxe2x80x9d is meant investigating an organism for the presence or absence of a property. The process may include measuring or detecting various properties, including the level of signal transduction and the level of interaction between a rdgB polypeptide and a NBP.
By xe2x80x9cdisease or conditionxe2x80x9d is meant a state in an organism, e.g., a human, which is recognized as abnormal by members of the medical community. The disease or condition may be characterized by an abnormality in one or more signal transduction pathways in a cell, preferably a cell listed in table 1, wherein one of the components of the signal transduction pathway is either a rdgB polypeptide or a NBP.
Specific diseases or disorders which might be treated or prevented, based upon the affected cells include: myasthenia gravis; neuroblastoma; disorders caused by neuronal toxins such as cholera toxin, pertusis toxin, or snake venom; acute megakaryocytic myelosis; thrombocytopenia; those of the central nervous system such as seizures, stroke, head trauma, spinal cord injury, hypoxia-induced nerve cell damage such as in cardiac arrest or neonatal distress, epilepsy, neurodegenerative diseases such as Alzheimer""s disease, Huntington""s disease and Parkinson""s disease, dementia, muscle tension, depression, anxiety, panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, schizophrenia, neuroleptic malignant syndrome, and Tourette""s syndrome. Conditions that may be treated by rdgB inhibitors include epilepsy, schizophrenia, extreme hyperactivity in children, chronic pain, and acute pain. Examples of conditions that may be treated by PYK2-rdgB pathway enhancers (for example a phosphatase inhibitor) include stroke, Alzheimer""s, Parkinson""s, other neurodegenerative diseases and migraine.
Preferred disorders include epilepsy, stroke, schizophrenia, and Parkinson""s disorder as there is an established relationship between these disorders and the function of potassium channels. See, McLean et al., Epilepsia 35:S5-S9 1994; Ricard-Mousnier et al., Neurophysiologie Cliniaue 23:395-421, 1993; Crit Rev. Veurobiol 7:187-203, 1994; Simon and Lin, Biophys. J. 64:A100, 1993; Birnstiel et al., Synapse (NY) 11:191-196, 1992; Coleman et al., Brain Res. 575:138-142 1992; Popolip et al., Br. J. Pharmacol 104:907-913, 1991; Murphyet al., Exp. Brain Res. 84:355-358, 1991; Rutecki et al., Epilepsia 32:1-2, 1991; Fisher and Coyle (ed), Frontiers of Clinical Neurosciene, Vol. 11 xe2x80x9cNeurotransmitters and Epilepsyxe2x80x9d; Meeting, Woods Hole Mass., USA IX+260P. John Wiley and Sons, Inc. NY, N.Y.; Treherne and Ashford, Neuroscience 40:523-532, 1991; Gehlert, Prog. Neuro-Psychopharmacol. Biol. Psychiatry 18:1093-1102, 1994; Baudy, Expert Opin Ther. Pat. 1994 4/4:343-378; Porter and Rogawski, Epilepsia 33:S1-S6, 1992; Murphy, J. Physiol. 453:167-183, 1992; Cromakalim, Drugs Future 17/3:237-239, 1992; Carmeliet, Eur. Heart J. 12:30-37, 1991; Olpe et al., Experientia 47/3:254-257, 1991; Andrade et al., Science 234/4781:1261-1265, 1986; Forster, J. Neurosci. Methods 13/3-4:199-212, 1985.
In preferred embodiments, the methods described herein involve identifying a patient in need of treatment. Those skilled in the art will recognize that various techniques may be used to identify such patients. For example, cellular potassium levels may be measured or the individuals genes may be examined for a defect.
By xe2x80x9cabnormalityxe2x80x9d is meant an a level which is statistically different from the level observed in organisms not suffering from such a disease or condition and may be characterized as either an excess amount, intensity or duration of signal or a deficient amount, intensity or duration of signal. The abnormality in signal transduction may be realized as an abnormality in cell function, viability or differentiation state. The present invention is based in part on the determination that such abnormality in a pathway can be alleviated by action at the PYK2-rdgB interaction site in the pathway. An abnormal interaction level may also either be greater or less than the normal level and may impair the normal performance or function of the organism. Thus, it is also possible to screen for agents that will be useful for treating a disease or condition, characterized by an abnormality in the signal transduction pathway, by testing compounds for their ability to affect the interaction between a rdgB polypeptide and PYK2, since the complex formed by such interaction is part of the signal transduction pathway. However, the disease or condition may be characterized by an abnormality in the signal transduction pathway even if the level of interaction between the rdgB polypeptide and NBP is normal.
By xe2x80x9cinteractxe2x80x9d is meant any physical association between polypeptides, whether covalent or non-covalent. This linkage can include many chemical mechanisms, for instance covalent binding, affinity binding, intercalation, coordinate binding and complexation. Examples of non-covalent bonds include electrostatic bonds, hydrogen bonds, and Van der Waals bonds. Furthermore, the interactions between polypeptides may either be direct or indirect. Thus, the association between two given polypeptides may be achieved with an intermediary agent, or several such agents, that connects the two proteins of interest (e.g., a rdgB polypeptide and PYK2). Another example of an indirect interaction is the independent production, stimulation, or inhibition of both a rdgB polypeptide and PYK2 by a regulatory agent. Depending upon the type of interaction present, various methods may be used to measure the level of interaction. For example, the strengths of covalent bonds are often measured in terms of the energy required to break a certain number of bonds (i.e., kcal/mol) Non-covalent interactions are often described as above, and also in terms of the distance between the interacting molecules. Indirect interactions may be described in a number of ways, including the number of intermediary agents involved, or the degree of control exercised over the rdgB polypeptide relative to the control exercised over PYK2 or another NBP.
By xe2x80x9cdisruptxe2x80x9d is meant that the interaction between the rdgB polypeptide and PYK2 or a NBP is reduced either by preventing expression of the rdgB polypeptide, or by preventing expression of PYK2 or NBP, or by specifically preventing interaction of the naturally synthesized proteins or by interfering with the interaction of the proteins.
By xe2x80x9cpromotexe2x80x9d is meant that the interaction between a rdgB polypeptide and PYK2 or NBP is increased either by increasing expression of a rdgB polypeptide, or by increasing expression of PYK2 or a NBP, or by decreasing the dephosphorylating activity of the corresponding regulatory PTP (or other phosphatase acting on other phosphorylated signaling components) by promoting interaction of the rdgB polypeptide and PYK2 or NBP or by prolonging the duration of the interaction. Covalent binding can be promoted either by direct condensation of existing side chains or by the incorporation of external bridging molecules. Many bivalent or polyvalent linking agents are useful in coupling polypeptides, such as an antibody, to other molecules. For example, representative coupling agents can include organic compounds such as thioesters, carbodiimides, succinimide esters, diisocyanates, glutaraldehydes, diazobenzenes and hexamethylene diamines. This listing is not intended to be exhaustive of the various classes of coupling agents known in the art but, rather, is exemplary of the more common coupling agents. (See Killen and Lindstrom 1984, J. Immunol. 133:1335-2549; Jansen, F. K., et al., 1982, Immunological Rev. 62:185-216; and Vitetta et al., supra).
By xe2x80x9cNBPxe2x80x9d is meant a natural binding partner of a rdgB polypeptide that naturally associates with a rdgB polypeptide. The structure (primary, secondary, or tertiary) of the particular natural binding partner will influence the particular type of interaction between the rdgB polypeptide and the natural binding partner. For example, if the natural binding partner comprises a sequence of amino acids complementary to the rdgB polypeptide, covalent bonding may be a possible interaction. Similarly, other structural characteristics may allow for other corresponding interactions. The interaction is not limited to particular residues and specifically may involve phosphotyrosine, phosphoserine, or phosphothreonine residues. A broad range of sequences may be capable of interacting with rdgB polypeptides. One example of a natural binding partner may be pyk2, which is described above. Using techniques well known in the art, one may identify several natural binding partners for rdgb polypeptides such as by utilizing a two-hybrid screen.
By xe2x80x9csignal transduction pathwayxe2x80x9d is meant the sequence of events that involves the transmission of a message from an extracellular protein to the cytoplasm through a cell membrane. The signal ultimately will cause the cell to perform a particular function, for example, to uncontrollably proliferate and therefore cause cancer. Various mechanisms for the signal transduction pathway (Fry et al., Protein Science, 2:1785-1797, 1993) provide possible methods for measuring the amount or intensity of a given signal. Depending upon the particular disease associated with the abnormality in a signal transduction pathway, various symptoms may be detected. Those skilled in the art recognize those symptoms that are associated with the various other diseases described herein. Furthermore, since some adapter molecules recruit secondary signal transducer proteins towards the membrane, one measure of signal transduction is the concentration and localization of various proteins and complexes. In addition, conformational changes that are involved in the transmission of a signal may be observed using circular dichroism and fluorescence studies.
In another aspect the invention features a method of diagnosis of an organism for a disease or condition characterized by an abnormality in a signal transduction pathway that contains an interaction between a rdgB polypeptide and PYK2 or a NBP. The method involves detecting the level of interaction as an indication of said disease or condition.
By xe2x80x9corganismxe2x80x9d is meant any living creature. The term includes mammals, and specifically humans. Preferred organisms include mice, as the ability to treat or diagnose mice is often predictive of the ability to function in other organisms such as humans.
By xe2x80x9cdiagnosisxe2x80x9d is meant any method of identifying a symptom normally associated with a given disease or condition. Thus, an initial diagnosis may be conclusively established as correct by the use of additional confirmatory evidence such as the presence of other symptoms. Current classification of various diseases and conditions is constantly changing as more is learned about the mechanisms causing the diseases or conditions. Thus, the detection of an important symptom, such as the detection of an abnormal level of interaction between rdgB polypeptides and PYK2 or NBPs may form the basis to define and diagnose a newly named disease or condition. For example, conventional cancers are classified according to the presence of a particular set of symptoms. However, a subset of these symptoms may both be associated with an abnormality in a particular signalling pathway, such as the ras21 pathway and in the future these diseases may be reclassified as ras21 pathway diseases regardless of the particular symptoms observed.
Yet another aspect of the invention features a method for treatment of an organism having a disease or condition characterized by an abnormality in a signal transduction pathway. The signal transduction pathway contains an interaction between a rdgB polypeptide and PYK2 or a NBP and the method involves promoting or disrupting the interaction, including methods that target the rdgB:NBP interaction directly, as well as methods that target other points along the pathway.
By xe2x80x9cdominant negative mutant proteinxe2x80x9d is meant a mutant protein that interferes with the normal signal transduction pathway. The dominant negative mutant protein contains the domain of interest (e.g., an rdgB polypeptide or PYK2 or a NBP), but has a mutation preventing proper signaling, for example by preventing binding of a second domain from the same protein. One example of a dominant negative protein is described in Millauer et al., Nature Feb. 10, 1994. The agent is preferably a peptide which blocks or promotes interaction of the rdgB polypeptide and PYK2 or another NBP. The peptide may be recombinant, purified, or placed in a pharmaceutically acceptable carrier or diluent.
An EC50 or IC50 of less than or equal to 100 xcexcM is preferable, and even more preferably less than or equal to 50 xcexcM, and most preferably less that or equal to 20 xcexcM. Such lower EC50""s or IC50""s are advantageous since they allow lower concentrations of molecules to be used in vivo or in vitro for therapy or diagnosis. The discovery of molecules with such low EC50""s and IC50""s enables the design and synthesis of additional molecules having similar potency and effectiveness. In addition, the molecule may have an EC50 or IC50 less than or equal to 100 xcexcM at one or more, but not all cells chosen from the group consisting of parathyroid cell, bone osteoclast, juxtaglomerular kidney cell, proximal tubule kidney cell, distal tubule kidney cell, cell of the thick ascending limb of Henle""s loop and/or collecting duct, central nervous system cell, keratinocyte in the epidermis, parafollicular cell in the thyroid (C-cell), intestinal cell, trophoblast in the placenta, platelet, vascular smooth muscle cell, cardiac atrial cell, gastrin-secreting cell, glucagon-secreting cell, kidney mesangial cell, mammary cell, beta cell, fat/adipose cell, immune cell and GI tract cell.
By xe2x80x9ctherapeutically effective amountxe2x80x9d is meant an amount of a pharmaceutical composition having a therapeutically relevant effect. A therapeutically relevant effect relieves to some extent one or more symptoms of the disease or condition in the patient; or returns to normal either partially or completely one or more physiological or biochemical parameters associated with or causative of the disease or condition. Generally, a therapeutically effective amount is between about 1 nmole and 1 xcexcmole of the molecule, depending on its EC50 or IC50 and on the age and size of the patient, and the disease associated with the patient.
In another aspect, the invention describes a polypeptide comprising a recombinant rdgB polypeptide or a unique fragment thereof. By xe2x80x9cunique fragment,xe2x80x9d is meant an amino acid sequence present in a full-length rdgB polypeptide that is not present in any other naturally occurring polypeptide. Preferably, such a sequence comprises 6 contiguous amino acids present in the full sequence. More preferably, such a sequence comprises 12 contiguous amino acids present in the full sequence. Even more preferably, such a sequence comprises 18 contiguous amino acids present in the full sequence.
By xe2x80x9crecombinant rdgB polypeptidexe2x80x9d is meant to include a polypeptide produced by recombinant DNA techniques such that it is distinct from a naturally occurring polypeptide either in its location (e.g., present in a different cell or tissue than found in nature), purity or structure. Generally, such a recombinant polypeptide will be present in a cell in an amount different from that normally observed in nature.
In another aspect, the invention describes a recombinant cell or tissue containing a purified nucleic acid coding for a rdgB polypeptide. In such cells, the nucleic acid may be under the control of its genomic regulatory elements, or may be under the control of exogenous regulatory elements including an exogenous promoter. By xe2x80x9cexogenousxe2x80x9d it is meant a promoter that is not normally coupled in vivo transcriptionally to the coding sequence for the rdgB polypeptide.
In another aspect, the invention features a rdgB polypeptide binding agent able to bind to a rdgB polypeptide. The binding agent is preferably a purified antibody which recognizes an epitope present on a rdgB polypeptide. Other binding agents include molecules which bind to the rdgB polypeptide and analogous molecules which bind to a rdgB polypeptide.
By xe2x80x9cpurifiedxe2x80x9d in reference to an antibody is meant that the antibody is distinct from naturally occurring antibody, such as in a purified form. Preferably, the antibody is provided as a homogeneous preparation by standard techniques. Uses of antibodies to the cloned polypeptide include those to be used as therapeutics, or as diagnostic tools.
In another aspect, the invention provides a nucleic acid molecule comprising a nucleotide sequence that encodes: (a) a polypeptide having an amino acid sequence set forth in SEQ ID NO:4 from amino acid residues 1-616 or 616-974; (b) the complement of the nucleotide sequence of (a); (c) a polypeptide having an amino acid sequence set forth in SEQ ID NO:5 from amino acid residues 1-250, 250-900, or 900-1243; (d) the complement of the nucleotide sequence of (c); (e) a polypeptide having an amino acid sequence of SEQ ID NO:6 from amino acid residues 1-251, 251-985, or 985-1349; or (f) the complement of the nucleotide sequence of (e). The utility of such isolated domains in the design of protein inhibitors is well-known to those skilled in the art.
The invention also provides an isolated nucleic acid molecule comprising a nucleotide sequence that encodes a polypeptide having the full length amino acid sequence set forth in SEQ ID NO:4; SEQ ID NO:5, or SEQ ID NO:6 except that it lacks at least one, but not more than two, of the domains selected from the group consisting of the, PIT, the central domain, the PYK2 binding domain, the calcium binding domain and the nucleotide binding domain. Such deletion mutants are useful in the design of assays for protein inhibitors. The nucleic acid molecules described above may be, for example, cDNA or genomic DNA and may be placed in a recombinant vector or expression vector. In such a vector, the nucleic acid preferably is operatively associated with the regulatory nucleotide sequence containing transcriptional and translational regulatory information that controls expression of the nucleotide sequence in a host cell.
Thus, the invention also provides a genetically engineered host cell containing any of the nucleotide sequences described herein and the nucleic acid preferably is operatively associated with the regulatory nucleotide sequence containing transcriptional and translational regulatory information that controls expression of the nucleotide sequence in a host cell. Such host cells may obviously be either prokaryotic or eukaryotic.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.